Abbess Vs. Prioress

[Feankie]

I just started reading Mother Dolores Hart's autobiography and am royally confused. She is the Prioress but there is also an Abbess. What's up with that?!

[Theoketos]

An abbess is a higher rank an usually oversees a large monastery. A prioress is either the head of a group of religious becoming an abbey or the abbesses' right hand (wo)man.